Electrocatalytic conversion of waste polyamide‐66 hydrolysates into high‐added‐value adiponitrile and hydrogen fuel

Abstract To reduce environmental pollution and plastic recycling costs, polyamide‐66 (PA‐66) as the most consumed engineering polymer needs to be recycled effectively. However, the existing recycling methods cannot convert waste PA‐66 into valuable chemicals for upcycling under ambient conditions. Here, we report an integrated hydrolysis and electrocatalytic process to upcycle waste PA‐66 into valuable adiponitrile (ADN), adipic acid, and H 2 commodities, thereby closing the PA‐66 loop. To enable electrooxidation of the PA‐66 hydrosylate hexamethylenediamine (HMD), we fabricated anode catalysts with hierarchical Ni 3 S 2 @Fe 2 O 3 core‐shell heterostructures comprising spindle‐shaped Ni 3 S 2 cores and Fe 2 O 3 nanosheet shells. The unique core‐shell architecture and synergy of the Ni 3 S 2 and Fe 2 O 3 catalysts enabled the selective dehydrogenation of C–N bonds from HMD to nitrile C≡N bonds, forming ADN with near‐unity Faradaic efficiency at 1.40 V during the 100‐h stability test even at 100 mA cm −2 . X‐ray photoelectron spectroscopy revealed that the Ni(Fe) oxy(hydroxide) species formed were in the active state during oxidation, accelerating the activation of the amino C–N bond for dehydrogenation directly into the C≡N bonds.